As Florida's new teacher evaluation system based on FCAT results has started to kick in, now might be a good time to let everyone know how crazy it is.

It would be funny, except for the fact that teacher pay and job security will soon be riding on it.

The crux of the new system is the "value-added model" (VAM) scoring formula, which seeks to gauge a teacher's contribution to a student's standardized test performance. It tries to assign how much credit (or blame) a teacher gets by separating "factors unique to students and schools from factors unique to a classroom teacher."

"It definitely is a complex formula," said Tiffany Cowie, a Florida Department of Education spokeswoman. "But there's a reason for that – so we can get the most accurate assessment on an individual level."

The state has had some hiccups trotting out the new system. An initial batch of results was pulled from the state's website last week because it was riddled with errors, with teacher totals in some counties (like Broward) way off.

If state education officials can't get a simple thing like counting right, how can it be trusted to pull off this Rubik's Cube rating system?

The VAM scoring model will come into much bigger play next year, when it will count for 50 percent of teachers' overall evaluation scores and school districts won't be able to blow it off, like many districts (including Palm Beach County's) did this year. The rest of teachers' evaluation scores comes from classroom observation.

In trying to gauge a teacher's testing impact, VAM uses a student's past test results and a host of variables like attendance, class size and "homogeneity of entering test scores in the class" to project the student's performance. The difference between that projection and the actual result gets ascribed to the teacher.

Even though most teachers were rated "effective" and "highly effective" this year, I've heard from many South Florida teachers dismayed by the system. They say they don't know what's expected of them, can't find out how their students are projected to perform, and wonder how negative factors beyond their control – like a student who takes drugs or doesn't eat or sleep before a test – can get pinned on them.

One seventh-grade math teacher who was rated "needs improvement" called the murky VAM system "the secret sauce that's ruining our lives." She teaches in a Broward middle school where most students are poor minorities. If she gets another subpar rating in the next two years, she can be fired.

At least she's being assessed on her students in her subject area. That's not the case for specialty teachers, whose evaluations are based on schoolwide scores of students they might never have taught in subjects out of their field.

No wonder public teacher morale is so low.

High-stakes testing in Florida started under former Republican governor Jeb Bush, but tying teacher pay and job security to test scores has been pushed by Democrats like President Obama and his education secretary, Arne Duncan, through the federal Race To The Top program.

Florida's Republican-dominated Legislature passed a teacher evaluation bill (SB736) pegged to tests last year, and the VAM model was recommended by a committee convened by Florida's department of education. The Student Growth Implementation Committee, which included teachers, administrators and parents, got input on the VAM model from a private contractor, the American Institutes for Research.

After I wrote about the new evaluation system earlier this week, I heard from one Broward teacher leaving next term after 12 years.

"The increase in teaching time, students per class and 'accountability' has come with the exact opposite in pay, [benefits] and respect for the profession," he wrote by email.

His next job: Working at a federal prison.

When it's gotten to the point that a teacher would rather be with inmates than our kids, you know something is seriously wrong.